The U.S. Food and Drug Administration issued a complete response letter rejecting Biohaven’s NDA for troriluzole to treat spinocerebellar ataxia, citing problems with reliance on externally controlled, real-world evidence and potential biases. Biohaven said the submission had followed prior agency discussions but now must reassess its evidence package. The company announced plans to cut annual R&D spending by roughly 60% and reprioritize programs, and its stock plunged on the news.